This application is related to and claims priority from Japanese Patent Application No. 2001-270821 filed on Sep. 6, 2001, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a heat storage tank in which a non-compressive fluid such as a hot water is thermally insulated and stored, and is suitably applied to a vehicle heat storage tank in which cooling water (hot water) for cooling a vehicle engine is thermally insulated and stored.
2. Description of Related Art
For example, in a heat storage tank proposed in U.S. patent application Publication No. 2002-0040693 A1, an elbow pipe portion, where a water introduction passage is bent by an approximate right angle, is formed at a lower side portion of a tank body, for supplying water into the tank body. Therefore, a relative large pressure loss (bending loss) is readily caused, and water-flow resistant becomes larger.
In view of the above problem, it is an object of the present invention to provide a heat storage tank that can effectively restrict a pressure loss of a fluid in an elbow pipe member.
According to the present invention, in a heat storage tank having a tank body for thermally insulating and storing a fluid, an elbow pipe member defining an introduction passage communicating with the tank body includes a first cylinder portion having an introduction port for introducing the fluid, and a second cylinder portion having a discharge port from which the fluid introduced from the introduction port is injected into the tank body. The first cylinder portion and the second cylinder portion are connected to have a corner portion therebetween. Further, the heat storage tank includes a discharge pipe member defining a discharge passage having an introduction port from which the fluid in the tank body is introduced to be discharged outside the tank body through the discharge passage. In the heat storage tank, a step portion is disposed in the elbow pipe member around a position where an axial line of the first cylinder portion and an axial line of the second cylinder portion are substantially crossed with each other. Further, the step portion has a protrusion end surface protruding toward the corner portion, a collision surface extending from the protrusion end surface, to which the fluid flowing from the first cylinder portion collides, and a guide surface extending from the protrusion end surface for guiding the fluid flowing from the first cylinder portion toward the discharge port in the second cylinder portion. Accordingly, the fluid flowing from the introduction port of the first cylinder portion collides with at least the step portion and an inner surface of the second cylinder portion at plural positions, while a flow direction of the fluid is turned in the elbow pipe member. Thus, it can restrict the flow of the fluid from being greatly disturbed, and a pressure loss in the elbow pipe member can be reduced.
Preferably, the step portion is constructed so that a flow rate of the fluid becomes larger at a center portion in a flow distribution of the fluid flowing from the discharge port of the second cylinder portion. Therefore, the fluid can be uniformly introduced into the tank body from the discharge port of the second cylinder portion.
Further, the collision surface of the step portion is provided opposite to the introduction port of the first cylinder portion, and the collision surface of the step portion is provided to be positioned at a side of the introduction port of the first cylinder portion from an outer peripheral surface of the discharge pipe member. Therefore, a face space facing the introduction port of the first cylinder portion can be made larger, among the space around the discharge pipe member. Thus, the fluid is effectively guided by the step portion, and readily flows through the second cylinder portion without being greatly affected by the discharge pipe member. Accordingly, the pressure loss in the elbow pipe member can be effectively reduced.
In addition, the center line of the discharge pipe member is positioned opposite to a side of the introduction port, relative to the center line of the second cylinder portion. Therefore, the face space facing the introduction port of the first cylinder portion can be more readily made larger.
Preferably, the protrusion end surface of the step portion has a height dimension from a bottom surface of the first cylinder portion, and the height dimension of the protrusion end surface is made smaller than an inner diameter of the introduction port of the first cylinder portion such that a part of the step portion is positioned on a projection area of the introduction port of the first cylinder portion. Therefore, it can restrict the passage sectional area of the elbow pipe member at the corner portion from being greatly small due to the step portion. Accordingly, it can restrict the throttle loss from being increased in the elbow pipe member at the corner portion while the pressure loss in the elbow pipe member can be sufficiently reduced.